Abstract: To solve the problem of inaccurate control and information island in beer fermentation process, a monitoring and control expert system based on PROFIBUS for beer fermentation process is presented. The system combining the PROFIBUS and Intranet has three layers: product management layer, inspection schedule layer and direct control layer. It is a distributed control system and can share its information in intranet. The expert system, simulating human control method, can recognize the faults of the process, fault-tolerant control, and estimate the coupling grade of inputs and outputs in each fermentation phase. The applications of the system in some factories show that: the mean error is less than ±0.5℃ and the data about fermentation process can be shared in Intranet. Therefore the system provides some good references for similar projects.